Degradation Of Rhodamine B With Peroxymonosulfate Oxidation Catalyzed By Cobalt-supported Hollow Nanosphere

Considering the inherent defects of Fenton reaction and its derivative reactions,advanced oxidation processes based on sulfate radical?SO4·-??SR-AOPs?have been attracting more and more attention as a promising alternative for the efficient degradation of stubborn organic compounds in water.Among a number of methods,peroxymonosulfate activated by cobalt has been studied extensively for generating sulfate radicals.The existing cobalt-supported catalysts have problems such as low cobalt utilization,complicated synthesis process and serious cobalt leakage.Based on the above research background,this paper intends to optimize the hydrothermal reaction conditions to synthesis economical and efficient heterogeneous cobaltsupported catalyst,not only to overcome the above shortco mings,but also to activate peroxymonosulfate effectively and to remove target conta minants efficiently.In this study,cobalt???acetylacetonate is used as the precursor and SiO₂ nanospheres as the template.The cobalt-supported hollow nanospheres are prepared by one step hydrothermal method at the reaction temperature of 180 ? and the reaction time of 12 h.The characterization result shows that the prepared cobalt silicate hydroxide hollow nanospheres are amorphous and pure.The dosage of SiO₂ template has a great influence on the morphology and physicochemical properties of the catalyst.With the increase of the template,the morphology of the catalyst changs from mesoporous sphere to hollow sphere,the specific surface area and unit pore volume increase while the cobalt content decreases.The specific surface area of CSH-80 is 492 m2/g,the unit pore volume is 1.632 cm3/g and the cobalt content is 21.7%.In the sulfate radical advanced oxidation system of this experiment,the initial concentration of rhodamine B is 100 mg/L,the dosage of catalyst is 0.1 g/L,the dosage of PMS is 0.35 mmol/L,the initial p H is 7.0±0.2 and the temperature is 20±1?.Respective catalyst CSH-80 not only shows high catalytic performance and the lowest cobalt leakage,but also good recycle property and structural stability.Degradation efficiency is susceptible to a series of factors.The degradation efficiency decreases with the initial concentration of rhodamine B increased.The increase of catalyst or PMS reduces the degradation efficiency.The reaction temperature?20 to 40??almost makes no change to the removal rate.Neutral p H is more suitable for PMS@CSH-80 system and humic acid will slow down the degradation process.In addition,PMS@CSH-80 system can degrade different types of typical organic micropollutants and behave well in natural water bodies,with the capacity to be applied in actual water treatment projects.Finally,it is proved that the surface catalytic mechanism of heterogeneous catalysts plays a leading role,and the adsorption removal mechanism and co balt ion catalytic mechanism only play a supporting role in PMS@CSH-80 system.At the same time,the main oxidative activator is detected to be sulfate radical?SO4·-?in this system,and the mechanism of the degradation of rhodamine B in PMS@CSH-80 system is inferred.